Comment # 17
on bug 111482
from Robert
Thanks Andrew! I played around a little bit with the refresh rates. Between 40-60Hz there is no difference in idle power consumption. The mem clock stays at 875Mhz and can't be changed. The best refresh rate with 8W idle power consumption I could get was at 39Hz: cvt12 5120 1440 39 -b xrandr --output DisplayPort-2 --newmode "5120x1440_39.00_rb2" 297.51 5120 5128 5160 5200 1440 1453 1461 1467 +hsync -vsync xrandr --output DisplayPort-2 --addmode DisplayPort-2 "5120x1440_39.00_rb2" xrandr --output DisplayPort-2 --mode "5120x1440_39.00_rb2" This causes the mem clock to go up to 625Mhz at first but it can be switched back to 100Mhz with echo "0" > /sys/class/drm/card0/device/pp_dpm_mclk Regarding my statement when using 30Hz in the last comment: """ It basically works but moving windows a little bit faster or moving the mouse pointer around looks "interesting". """ For this "flickering" that I saw and which was quite annoying I found a workaround :-) It looked like something didn't refresh fast enough. So I thought playing around with some frequencies would be a good idea... And the mem clock was the obvious one to start with. So I was setting the mem clock to 500Mhz with echo "1" > /sys/class/drm/card0/device/pp_dpm_mclk Then the "flickering" went away :-) But of course that brought idle power consumption to 24W. So just for fun I switched back to 100Mhz with echo "0" > /sys/class/drm/card0/device/pp_dpm_mclk Funny enough the "flickering" stayed away :-))) So for now after I start KDE plasma I enter Konsole and execute echo "1" > /sys/class/drm/card0/device/pp_dpm_mclk echo "0" > /sys/class/drm/card0/device/pp_dpm_mclk and be happy :D One final observation: I tried out kernel 5.3-rc8. With that kernel there is no way to reduce idle power consumption. It stays at 34W regardless what you do. But with this tag https://cgit.freedesktop.org/~agd5f/linux/tag/?h=drm-next-5.4-2019-08-30 (which basically is kernel 5.3-rc3 with the Navi10 patches for kernel 5.4 - if I got it right ;-) ) idle power consumption is as expected. So my whole issue basically comes down to this: If you have a resolution of 5120x1440 and a refresh rate of > 39Hz your idle power consumption stays at max and there is (at least until now) nothing you can do about it. So if I had used a lower resolution or a smaller screen I wouldn't have had an issue at all ;-) S... happens :D But anyways: Thanks so much for your help and also to Ilia! I'm now happy with my setup so far. It would be very interesting if there is really some kind of a cap with 5120x1444@39Hz or if this this "only" a firmware problem, a driver problem, a config error or something completely different. Maybe we'll find out in our next lives :D
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